Answer Posted / lakshminarayana reddy

2 types
1. Implicit locks: oracle automatically locks the rows
whenever user performs DML operations.
2. Explicit locks: provided by user.
2 tpyes a) Row level locks: used to lock selected rows
of table.It is imposed by "for update" clause in select.
b) Table level locks: used to lock compleate
table. 3 models 1) share mode
2) share update
3) exlcusive mode

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